The energy band alignment of X(c), Gamma(c), and Gamma(v) points in (Al0.7Ga0.3)(0.5)In0.5P/AlxIn1-xP heterostructures

Better carrier confinement in 0.6-mu m-band laser diodes can be achieved by incorporating an AlInP layer into the (Al0.7Ga0.3)(0.5)In0.5P cladding layers. The effectiveness of this heterostructure, though, cannot be analyzed without detailed knowledge of the energy band alignment at the X(c), Gamma(c), and Gamma(upsilon) band extrema. We conducted photoluminescence and photoreflectance measurements at 12-100 K on (Al0.7Ga0.3)(0.5)In0.5P/AlxIn1-xP heterostructures (x=0.47-0.61) free from long-range ordering, and analyzed the results to obtain basic data on the alignment scheme. In these measurements we observed the Gamma(c) to Gamma(upsilon) and the X(c) to Gamma(upsilon) transitions in bulk Al0.53In0.47P and (Al0.7Ga0.3)(0.5)In0.5P alloys, the AlxIn1-xP X(c) to (Al0.7Ga0.3)(0.5)In0.5P Gamma(upsilon) transition in (Al0.7Ga0.3)(0.5)In0.5P/AlxIn1-xP superlattices, and the X(c) to Gamma(upsilon) and to the Gamma(c) to Gamma(upsilon) transitions in 20-nm-wide AlxIn1-xP layers in (AlyGa1-y)(0.5)In0.5P/AlxIn1-xP/(AlyGa1-y)(0.5)In0.5P double heterostructures (x=0.33-0.39, y=0.7-1.0). We found that the energy level of X(c) in AlxIn1-xP decreased by 0.09 eV as x increased from 0.47 to 0.61, the X(c) of AlxIn1-xP crossed the Gamma(c) at 0.340 (+/-0.008), and the Gamma(upsilon) of AlxIn1-xP crossed the Gamma(upsilon) of (Al0.7Ga0.3)(0.5)In0.5P at x=0.47(+/-0.01). The share of the band offset at Gamma(c) for x=0.53 was 75(+/-3)%. (C) 1997 American Institute of Physics.